title: Targeted gene delivery with noncovalent electrostatic conjugates of sgc-8c aptamer and polyethylenimine.
abstract: BACKGROUND
  Several strategies have been shown to improve the transfection efficiency of polyethylenimine (PEI) as a nonviral gene delivery vector. In the present study, a nucleic acid aptamer specific for protein tyrosine kinase 7 (PTK7) surface marker, sgc-8c, was conjugated electrostatically to pre-formed 10-kDa PEI/plasmid DNA polyplexes, and the ability of the conjugate to transfer genetic material was evaluated in MOLT-4 human acute lymphoblastic leukemia T-cells, which express PTK7 on their surface.
  
  
  METHODS
  Polyplexes (plasmid DNA-vector conjugates), prepared using PEI-sgc-8c conjugate and pCMVLuc as a reporter gene, were characterized in terms of particle size, surface charge and the extent of DNA condensation. Polyplexes were also evaluated for cytotoxicity using the MTS colorimetric assay, as well as for transfection efficiency in MOLT-4 cells, and compared with the results obtained in U266 cells, which lack cell surface PTK7.
  
  
  RESULTS
  Relative to pDNA/PEI, the size of pDNA/PEI/sgc-8c aptamer polyplexes increased with decreasing zeta potential. In MOLT-4 cells, pDNA/PEI/sgc-8c aptamer polyplexes exhibited an almost six- to eight-fold increase in transfection efficiency compared to that of pDNA/PEI polyplex, indicating that conjugation of sgc-8c aptamer to pre-formed 10-kDa PEI/plasmid DNA polyplexes achieved effective targeting without covalent attachment, whereas receptor-mediated conducted transfection was confirmed by performing a competitive transfection experiment and a cellular uptake study.
  
  
  CONCLUSIONS
  The results of the present study provide an example of the usefulness of a nucleic acid aptamer in the form of noncovalent, electrostatic conjugates as an approach for enhancing the transfection efficiency of a polycation vector such as PEI without significant induced cytotoxicity.
authors.affiliation: Pharmaceutical Research Centre, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Nasim
authors.initials: N
authors.lastname: Shahidi-Hamedani
authors.forename: Wayne T
authors.initials: WT
authors.lastname: Shier
authors.forename: Faezeh
authors.initials: F
authors.lastname: Moghadam Ariaee
authors.forename: Khalil
authors.initials: K
authors.lastname: Abnous
authors.forename: Mohammad
authors.initials: M
authors.lastname: Ramezani
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry* / Q000235:genetics; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D003124:Colorimetry; D005434:Flow Cytometry; D018014:Gene Transfer Techniques; D006162:Guanylate Cyclase / Q000737:chemistry* / Q000235:genetics; D006801:Humans; D010316:Particle Size; D011094:Polyethyleneimine / Q000737:chemistry* / Q000633:toxicity; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry* / Q000235:genetics; D000071756:Soluble Guanylyl Cyclase; D055672:Static Electricity; D014162:Transfection
chemical_list: D052157:Aptamers, Nucleotide; D018160:Receptors, Cytoplasmic and Nuclear; D011094:Polyethyleneimine; D006162:Guanylate Cyclase; D000071756:Soluble Guanylyl Cyclase
keywords: acute lymphoblastic leukemia; aptamer; nanoparticle; polyethylenimine; targeted delivery